| 摘要 |
PURPOSE:To send an alarm sound without fail and to execute securely an emergency communication even when the hook off of the receiver of an extension telephone set is not noticed and an emergency communication message is not heared even when the receiver is hooked off by supervising the response of the extension for a constant time and sending an alarm sound to the extension telephone set after the constant time passes. CONSTITUTION:When the receiver of an extension telephone set is hooked off at the time of the emergency communication and by the starting of the emergency communication, and channel switching relay contact 301 switches the channel of an extension telephone set 001 from a private branch telephone exchange 002 to an emergency private branch communication equipment side, an extension response supervisory circuit 101 immediately detects that the receiver of the extension telephone set 001 is hooked off, a primary switching relay 202 is operated and a message from an emergency communication message sending circuit 105 is sent through a contact 303. The extension response supervisory circuit 101 simultaneously starts a time interval circuit 102, and therefore, after the constant time lapses, a secondary switching relay 203 is operated, the channel is switched from the emergency communication message sending circuit up to the present to an alarm sound sending circuit and the alarm sound is sent to the extension telephone set 001.
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